Fabled fast starter (4)
I believe the answer is:
'fabled fast starter' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hare that I've seen before include "Sort of rabbit" , "'Swift, long-eared animal (4)'" , "Rabbit-like animal" , "may be electric!" , "Rabbit-like creature" .)